src/main/java/net/pterodactylus/sonitus/data/filter/RateLimitingFilter.java

   1 /*
   2  * Sonitus - DelayFilter.java - Copyright © 2013 David Roden
   3  *
   4  * This program is free software: you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation, either version 3 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 package net.pterodactylus.sonitus.data.filter;
  19
  20 import static com.google.common.io.Closeables.close;
  21
  22 import java.io.EOFException;
  23 import java.io.IOException;
  24 import java.io.PipedInputStream;
  25 import java.io.PipedOutputStream;
  26 import java.util.Arrays;
  27 import java.util.logging.Logger;
  28
  29 import net.pterodactylus.sonitus.data.ConnectException;
  30 import net.pterodactylus.sonitus.data.Connection;
  31 import net.pterodactylus.sonitus.data.Filter;
  32 import net.pterodactylus.sonitus.data.Format;
  33 import net.pterodactylus.sonitus.data.Source;
  34
  35 import com.google.common.base.Preconditions;
  36
  37 /**
  38  * Rate limiting filter that only passes a specified amount of data per second
  39  * from its {@link Source} to its {@link net.pterodactylus.sonitus.data.Sink}.
  40  *
  41  * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
  42  */
  43 public class RateLimitingFilter implements Filter {
  44
  45         /** The logger. */
  46         private static final Logger logger = Logger.getLogger(RateLimitingFilter.class.getName());
  47
  48         /** The limiting rate in bytes/second. */
  49         private final int rate;
  50
  51         /** The source’s format. */
  52         private Format format;
  53
  54         /** The input stream to read from. */
  55         private PipedInputStream pipedInputStream = new PipedInputStream();
  56
  57         /**
  58          * Creates a new rate limiting filter.
  59          *
  60          * @param rate
  61          *              The limiting rate (in bytes/second)
  62          */
  63         public RateLimitingFilter(int rate) {
  64                 this.rate = rate;
  65         }
  66
  67         //
  68         // FILTER METHODS
  69         //
  70
  71         @Override
  72         public Format format() {
  73                 return format;
  74         }
  75
  76         @Override
  77         public byte[] get(int bufferSize) throws EOFException, IOException {
  78                 byte[] buffer = new byte[bufferSize];
  79                 int read = pipedInputStream.read(buffer);
  80                 if (read == -1) {
  81                         throw new EOFException();
  82                 }
  83                 return Arrays.copyOf(buffer, read);
  84         }
  85
  86         @Override
  87         public void connect(Source source) throws ConnectException {
  88                 Preconditions.checkNotNull(source, "source must not be null");
  89
  90                 format = source.format();
  91                 final long start = System.currentTimeMillis();
  92                 try {
  93                         pipedInputStream = new PipedInputStream();
  94                         final PipedOutputStream pipedOutputStream = new PipedOutputStream(pipedInputStream);
  95                         new Thread(new Connection(source) {
  96
  97                                 @Override
  98                                 protected int bufferSize() {
  99                                         return rate;
 100                                 }
 101
 102                                 @Override
 103                                 protected void feed(byte[] buffer) throws IOException {
 104                                         long waitTime = 1000 * buffer.length / rate;
 105                                         long now = System.currentTimeMillis();
 106                                         pipedOutputStream.write(buffer);
 107                                         pipedOutputStream.flush();
 108                                         while ((System.currentTimeMillis() - now) < waitTime) {
 109                                                 try {
 110                                                         long limitDelay = waitTime - (System.currentTimeMillis() - now);
 111                                                         logger.finest(String.format("Waiting %d ms...", limitDelay));
 112                                                         Thread.sleep(limitDelay);
 113                                                 } catch (InterruptedException ie1) {
 114                                                         /* ignore, keep looping. */
 115                                                 }
 116                                         }
 117                                 }
 118
 119                                 @Override
 120                                 protected void finish() throws IOException {
 121                                         close(pipedInputStream, true);
 122                                         close(pipedOutputStream, true);
 123                                 }
 124                         }).start();
 125                 } catch (IOException ioe1) {
 126                         throw new ConnectException(ioe1);
 127                 }
 128         }
 129
 130 }